... is an efficient boring rig in big-bore pile-base project construction, which mainly applies to such base constructions as ... speedr/min2.5We are Shandong Hongda Construction Machinery Group Co., Ltd., a professional construction machinery manufacturer with a history ... , hammer-head, flat-top, multi-speed, stepless-speed), Construction Elevators(multi-speed, stepless-speed), Concrete Mixers (rotary-drum- ...